Electrical relay



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NSNNBNBNN INVENTUR. Clarerc ,51, Szazfely BY H115' ATZRNEY Patented Feb. 5, 1952 UNITED STATES FATJNT OFFlCE ELECTRICAL RELAY Vania Application August 28, 1947, Serial No. '771,024

37 Claims. (Cl. 171-97) My invention relates to electrical relays, and particularly to relays having a high ratio of release to pickmp, adapted for, although in no way limited to, association with a bus bar in such a manner that direct current in the bus bar serves as the exciting current for the relay.

Bus bar relays provide a means for eiiecting a control or controls directly in response to the magnetic `field established by current flowing in the associated bus bar. In certain applications these relays are required to have a high ratio oi release to picloup; to be accurately controlled; to be free from variations in operation due -to changes in ambient temperature; and to operate properly under conditions of heavy vibration and shock of the type encountered, for example, when mounted for use on railway locomotives.

It is an object of my invention to provide a novel and improved relay having a high ratio of release to pick-up, employing sturdy, rugged parts arranged so as o operate properly when subjected to irregular shocks and vibrations of relatively large magnitude.

Another object is to provide a compact relay organization adapted for mounting in associa tion with a bus bar so that current in the bus bar serves as the exciting current for the relay.

These stated and other important objects which will become apparent from the following description, are attained. by mounting an armature assembly for rotation about an axis passing through its center of mass so as to minimize the eiTect of shock and vibration on the assembly, by providing` a system of balanced forces on the armature assembly with the opposing forces working in common planes so as to minimize the turning moments of the forces relative to the pivots as fulcrums, by employing sturdy, rugged parts assembled together in such a manner as to prevent relative displacement of the parts while freely permitting adjustment of the assembly, by combining the relay parts in an assembly which permits mounting the armature assembly in the neutral space of a hollow conductor forming a part of a load circuit, by supprying the relay armature with flux from the external magnetic field of the conductor, and by providing means' for varying the amount o flux supplied to the armature from the external eld so as to provide a convenient, accessible means for adjusting the operating range of the relay.

The relay embodying my present invention is an improvement on the direct current responsive means disclosed and claimed in my copending application for Letters Patent of the United States, Serial No. 745,709, filed on May 3, 1947, now abandoned, and provides a control means which is an improvement on the relay systems disclosed and claimed in my copending application for Letters Patent of the United States, No. 732,771, liled March 6, 1947, now Patent No. 2,537,319, issued January 9, 1951.

I shall describe one form of an improved relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a top plan view, partially sectional, of the operating mechanism of an improved relay embodying my invention, with certain of the parts omitted in order better to illustrate the relationship of the remainder oi' the parts. Figs. 2 and 3 are secL tional views taken substantially on the lines .II-II and III-III of Fig. 1. Fig. 4 is a sectional view taken substantially on the line IV--IV of Fig. 3. Fig. 5 is a view showing details of certain parts oi the operating mechanism. Fig. 6 is a detail View showing the key l!) in operative relationship with gear plate I2. Fig. 7 is a graphical representation of certain of the torques developed in the relay and illustrating certain principles of operation of my relay. Fig. 8 is a schematic view representing an application of a pair of relays embodying my invention. Fig. 9 is a top view, partially sectional, illustrating the pair of relays embodying my invention as used in the application represented in Fig. 8.

Fig. l0 is a front view of the apparatus illustrated in Fig. 9. Fig. l1 is a top view partially sectional showing details of the magnetic strap assemblies. Fig. l2 is a sectional view taken substantially onv th'e line XII-XII of Fig. 11. Figs. 13 and lli are top and iront views, respectively, of a strap assembly represented in Fig. 12.

In each of the several views of the drawings similar reference characters refer to similar parts.

Referring to the drawings, an improved relay embodying my invention comprises an operating mechanism, a relay housing, and energizing means. A preferred form of the operating mechanism is illustrated in Figs. 1-4 inclusive, one form of the relay housing is illustrated in Figs. 8-10 inclusive, while Figs. 11 through ill, inclusive, illustrate one form of the energizing means. The several elements comprising one embodiment of my invention are illustrated in assembled relationship in Fig. 9 for use in a particular application schematically represented in Fie. 8.

of bore 3.

Referring first to Figs. 1 4, inclusive, of the drawings, the operating mechanism of a relay embodying my invention is arranged to exert on a rotor` mounted for movement between two ex treme positions, a system of forces comprised of two opposing sets of forces, one set including a force biasing the rotor to a position intermediate its two extreme positions, and another force biasing the rotor to its nearest extreme position; and the other set including a force biasing the rotor to a selected one of its two extreme positions, and another force resulting from the exciting current in the relay tending to operate the rotor from the biased one position to the other extreme position. The force system isapplied to the rotor in pianes perpendicular to the axis of rotation and in such a manner that the forces of each set oppose each other in common planes so as to minimize the turning moments of such forces relative to the points of support as er ulcrums. The force elements are selectedland proportioned so that the resultant torque established on the rotor under a given condition of eX- citing current in the relay results in operation of the'rotor from its released to its picked-up position, and under another condition or" energizing current in the relay results in operation oi' the rotor from its picked-up to its released position, with the magnitude of the other condition of energizing current being a relatively high per- :ff

'equi-distant from its two extreme positions,

while the more important elements ofthe mechanism can be seen best in an exploded view in Fig. 5. cally shaped frame member I (see Fig. 5) which supports in parallel spaced relationship one or more pairs of pole pieces 2, the pole pieces being inserted into and pinned in openings provided in member' I and projecting outwardly from the rear face of that member. The mount-ing of pole pieces 2' in member i is such that a central bore 3 provided in the front face of member I passes through the pole pieces 2 so that a considerable portionof the length o each pole piece is exposed along the inner face of the rim of bore 3. A centrally located opening 4 (see Fig. 2) provided in the bottom of the bore communicates vwith the rear face of member I and has mounted therein a pivot plate 5 provided with ahub .ex-

tending through opening 4 and acircularflange 'which rests against and is. riveted to the bottom Plate 5 has a through opening 6 in which is threaded a pivot 'I which may be'adjustably positioned in the opening and then locked into placeby a lock nut 8 screwed on the rearwardly extending portion of pivot l. The arrangement is such that pivot 'I lies in the central axis of thebore 3 and cylindrical member I. Other openings 9 (see Fig. 5) provided in member I are spaced from the center opening 4 and are provided for a purpose to be explained presently. Another opening I provides a communication from the rear face of member I to the side of bore 3 and is extended to the front face of the rim of member I by an opening II of reduced diameter. yThe openings lliA and. II

.have a functionthatalso will be explained in the following description.

A cylindrical gear plate I2 has a center open- The mechanism comprises a cylindri- -1 50 keys the two elements together.

ing adapted to t around the flange oi'. pivot plate and is provided on its outer edges with gear teeth I3. The rear face of plate I2 is formed with radial slots I4 (see Fig. 6) and the front face has an angle piece I5 secured thereto to which is riveted one end of an inwardly coiled spiral spring IG having its opposite end shaped to t into a slot II (see Fig. 4) formed in the hub of a non-magnetizable spider I8 provided with radial arms, one for each pair of pole pieces .mounted in member I. Each radial arm of spider I8 carries at its extreme end an armature in the form of a dependent magnetizable shoe I9 of U-,shaped configuration suitably secured as by rivets to the arm with the extended legs of the shoe being separated from each other (see Fig. 5) by a portion of the non-magnetizable arm. The upper faces of the shoe legs and the separating portion of the radial arm are shaped to conform to the inner surface of the central bore l3 provided iti-member I. Each radial arm has an opening 'communicating from the rear of the arm toa slot'2I formed on the front. A guide hole 22.in the side of spider I8 communicates with a centralopening 23 formed in the spider hub with the opening 23 being provided for receiving a shaft 24 molded into an insulating body member`25. The shaft 24 and body member 25 rare provided at their opposite ends with pivot openings 2G disposed in axial alignment. Body 25 'has moldedtherein a plurality of iiexible iin- `gers-.2l :whichextend radially outwardly from .the'axis Vofl the pivot openings 25, and also has molded'therein a magnetizable armature mem- .ber 28 which'passes through the rotor axis in a planecommon to the fingers 21 to project outwardlyonopposite sides of the body. The bottom face of body 25 is formed with a notch which is disposedfor alignment with slot 2| provided in the'radial arms of spider IB. The body and spider are assembled together by pressing shaft 24 intoopening 23 of the spider until the upper faces of the radial arms abut against the lower face of cody 25. The two elements assembled 5 in this manner are placed in a suitable mold ar ranged so that the notch in body 25 is brought into alignment with slot 2I of the radial arms. The openingsV 20 of the rff`ial arms are left exposed by the mold, and solidifiable material which vcan'bev applied ina liquid, molten or plastic condition and which will subsequently harden, is introduced through the holes 20 into the aligned Yslot and notch. A wide variety of different ma` terials. may beused, but I prefer to use 7 per cent Vantimonial lead .because it pours easily when Amolten;u and retains its dimensions while cooling. .The spider and body elements are left in the mold until the lead cools, and when the elements are removed .from the mold the solidiiied lead rigidly The previously mentioned guide hole 22 in one side of the spider hub I8 is then extended through shaft 24 and the opposite side of the spider hub, and a pin 30 (see Fig. 2) is pressed into the hole to assure maintenance of the established relationship of the spider and body elements. These two elements when assembled together in the manner just explained constitute the rotor of my relay.

Associated with the rotor are U-shaped magnetizable pole pieces which cooperate with .magnetizable armature member 28 and serve to support another pivot plate 36 provided with a secondpivot 3l (see 5) The two legs of each .pole piece 35 are arranged for disposition on ,Opposite sides of rotor body 25 with the con' Afronting surfaces of the pole pieces.

necting portions of the pole pieces extending over and across the body with suhicient clearance to permit pivot plate 36 to be carried from the con* necting portions so as to support pivot t1 for cooperation with pivot opening 2t provided in the upper face of body 25. The confronting faces of the connecting portions of pole pieces 35 are provided with indentations and projections the latter of which may, as shown, be in the form of rivets arranged so that their heads project free of the surfaces of the pole pieces, and pivot plate 3s also is provided with projections as in the form of headed rivets mounted in the plate with the head or" each rivet disposed free of the upper face of the plate. The pole pieces 35 are assembled in a mold in proper relationship to cooperate with armature 28 in a manner to be explained hereinafter, and with pivot plate 315 having its upper face abutting against the lower edges of the pole pieces: 35 so that the rivets carried by the plate are disposed between the con- Solidiable material in its liquid state, such as lead, is then poured into the mold so as to cause the material to iiow into the indentations and around the heads or" the rivets carried by the pivot plate and pole pieces. The parts are removed from the mold when the material solidiiies and pivot plate 35 is then held suspended from the conn necting portions of pole pieces 35. Each leg of the pole pieces 35 is drilled and threaded for receiving a tap bolt 4D projecting through aligned openings in a supporting member 4I provided for either end of the pole pieces 35 and in turn supported upon the rim of member I. The supporting member 4I is formed for lateral stability with a depending portion shaped to conform to the inner surface of the rim of member I and with a supporting ledge which is secured to the `upper surface of the rim as by tap screws #i2 (see Fig. 2). With the pole pieces 35 supported from frame member I through supporting members llI, pivot plate 36 is positioned so that its pivot 31 is in direct axial alignment with the other pivot 1 so that pivot openings 26 formed in the opposite ends of the rotor assembly will engage the pivots 1 and 31 to mount the rotor about an axis passing through its center of mass. A permanent magnet 43 provided for supplying fiux to the pole pieces 35 is held in magnetic relationship with the pole pieces by means of a v" clamping member IIII bearing against the upper face of magnet 43 and having dependent ears which prevent lateral displacement of the mag- `net. Clamping member M is suitably secured to the pole pieces 35 as by the medium of screws threaded into support members 4t in turn secured by screws 46a to the pole pieces 35. Each support member 46 is provided with a terminal post d1 sandwiched between two insulating strips 3.53 fastened by screws 49 to support member 46. terminal post 41 is threaded at its upper end to receive a terminal nut 50 and has its lower end bifurcated to receive a contact element 5| provided at its lower end with a slot in which mounted one end of a iiexible contact ribbon 52 coiled in a spiral with its other end fastened to a iiexible finger 2'! as by a contact button 53 riveting together the ribbon and linger. The biiurcated lower ends of terminal post 41 may be drawn tightly together by a bolt 54 for securel,7 clamping contact element 5I in post 41,

Associated with the ilexible fingers 21 are contact supports 55 secured by boltsy 51 tothe upper surface of supporting members 4I and provided with means of cooperating with the fingers 21.

Each contact support 55 has on one end a leg provided with a mold insulating member 68 carrying a threaded bushing 56 receiving a contact terminal 51 provided with a contact face 58 for engaging terminal button 53 of the mating finger 2i', the arrangement permitting terminal 51 to be adjustably positioned in its threaded bushing 55 and then locked into place by a nut 59 which also serves to secure a terminal wire to the contact terminal 51. The other end of support 55 also has a leg which may if desired be provided with a contact terminal 51 or as shown may be provided with an adjustable member Se mounted in a slotted opening in the leg for movement toward or away from the axis of rotation of the rotor.

.armature stops 64, each provided with a dependent leg carrying a core pin 65, are secured as by bolts 66 to the rim of member I on either side of each radial arm spider I8 to limit the rotation of the spider and consequently of the varmatures I9 thereby, between two extreme positions deiined respectively by the core pins 65.

In assembling the relay operating mechanism, spider I8 and body 25 are secured together in a manner previously explained so that shaft 2li projects beyond the end of the spider huh, and the other end of the spiral spring I5 is forced into hub I1 of the spider and is soldered into place. The assembly of gear plate I2 and the rotor is then lowered into bore 3 so that pivot opening 25 of shaft 24 engages pivot 1, and the central opening of gear plate I2 iits around the fdange oi pivot plate 5, with the gear plate having its rear face resting against the bottom of bore 3 so that some oi the radial slots of the gear plate are exposed by openings 9 of member I. Armature stops Eid are next secured to the rim of member and then pole pieces 35 carrying pivot plate 35 and fastened to supporting members 6I are slipped across body 25 so that pivot 3'.' enters pivot opening 26 formed in the upper face of body 25. The members 4I are then bolted to the rim of member I alongwith the contact supports 55 so that the rotor assembly is mounted for rotation about the pivots 1 and 31. The position of pivot 31 will be fixed with respect to the upper rim of member I, but pivot 1 is adjustable in opening 6 of pivot plate 5 so that by positioning pivot 1 the proper spacing of the pivots can easily be obtained, and then maintained by tightening lock nut 8.

With the elements of the operating mechanism assembled in the manner just described, the magnetizable shoes I9 carried at the ends of each radial arm are disposed in magnetic relationship with the associated pair of pole pieces 2 so as to function as armatures. While one or more pairs of pole pieces 2 and an equivalent number oi l radial arms for the spider may be employed in my relay, I prefer to use two pairs of pole pieces in order to provide for a balanced system of forces on the rotor, and the particular embodiment of my invention illustrated in the drawings utilizes two oi such pairs of pole pieces so that spider iii has two radial arms extending outwardly from the spider hub. The two pairs of pole pieces 2 are located on opposite sides of and radially equidistant from the axis of rotation of the rotor as defined by the centers of pivots 1 and with the two pole pieces of each pair spaced apart uniormly and as previously mentioned, the bore .3 in member I passes through each of the pole pieces so as to expose each of there for a con- .15 siderable portion of its length. rlhe magnetizable shoes lS carried at the end of each radial arm conform to the inner surface of bore 3 and the lengths of the radialarms proportioned so that the pole faces of the magnetisable shoes are disposed adjacent to the pole pieces 2 with clearance between the pole pieces and shoes suliicient freely to permit rotation of the rotor assembly about its pivots. The two pole faces formed at the ends of each magnetizable shoe I9 span the two pole pieces of each pair with the expose-l lace ci each pole piece 2 and the assoc ted pole face or" shoe i9 being donned by radii of bore drawn to either side of the exposed face or the pole piece.

The armature stops are secured to member l in such a manner that when cach radial arm of spider is equi-distant from its two coop ing stopsf. as illustrate in Ll, the pole of the magnet are displaced coun- *,:erclocltwise with re o the associated pole pieces 2 so that only confronts theA as 1^ words, a l i the roter to the c posed face of mid point the mediate position ,'oecaos-v e either direction from such a lesser amount of the shoe 1 when rotated in a counterclcckwi more of the shoe face to the rotated in a clockwise direction. ditions assumed above, an equal amount or rotation is permitted in either direction from the intermediate position, and preferably the total amount oi rotation between the tw positions defined by the armature stops limited to a small range of values such that Siux is supplied to each pair ci pole in a manner to be explained hereinafter, the torque developed on the. rotor due to the Flux acting on the magnetiaable shoes decreases substantially uniformly according as more of the shoe face is exposed to its, associated pole piece. rihe torque on the rotor for example, be represented the line o of Fig. '1, it being noted that the maxi- .f um. torque developed on the rotor when it is its extreme counter-clockwise where the least amount of shoe face is exposed to the pole pieces, and decreases at substantially uniform rate more of the shoe face becomes exposed until minimum torque is develope-d when the rotor its extreme clockwise stop. The line b ol Fig. 7 also illustrates the relationship of the toi-ques developed on the rotor by flux supplied by pole pieces E in the varios-.s different positions of the rotor, it being noted that line represents the condition cofrespondil` g to different level of in the pole pieces 2, a lower n aximum vali i'or the torque leing established at the counter iocliwise position oi the rotor.

The contact terminals 51 and adjustable members EQ carried on support 55 are so adjusted that with the rotor in its intermediate position as illustrated in Fig. l, the flexible iingers 21 carried by rotor body 25 just clear their associated terminals 51 and adjustable members 6D so that the fingers 21 are uniexed and do not provide any turning moment on the rotor assembly. When, however, the rotor is swung from its intermediate position toward its extreme counterclockwse position, a pair of ngers 21 on opposite sides of body 25 are driven into engagement with the matbis ing pair of contact terminals 51 so that the iingers become flexed to create a, torque which tends to restore the rotor` to its intermediate position. The fingers 21 are designed to exert on the rotor a torque which increases at a substantially uniform rate as the rotor is driven closer to its counterclockwise stop so that this torque reaches a maximum value when the rotor is in its extreme counterclockwise position. The torque developed by iingers 21 when displaced counterclockwise from its intermediate position may be represented by line c of Fig. 7, which extends between the two vertical lines of Fig. 7 representing respectively the counterclockwise and intermediate positions of the rotor. This torque is suflicient to establish a good electrical contact of low resistance between contact buttons 53 and contact faces 58 of the terminals 51, so that the contacts will be established when the rotor is in its extreme counterclockwise position and will be open when the rotor is in its intermediate position or is swung in the clockwise direction from its intermediate position. In this connection it should be noted that flexible contact ribbons 52 connecting terminal posts 41 to the flexible fingers 21 are arranged and proportioned in such a manner as to minimize the restricting effect of the connecting ribbon on the flexure of the associated finger 21. This is attained by employing a very thin flexible ribbon of considerable length formed in a coil.

When the rotor is displaced in a clockwise direction from its intermediate position the other pair of contact iingers 21 located on opposite sides of the rotor body 25 are driven into engagement with their associated adjustable members 63 so that these ngers become flexed to create a torque which increases uniformly as the rotor appreaches its clockwise stops. The torque developed by the fingers 21 on the rotor when it is displaced in the clockwise direction about its intermediate position may be represented by the line d of Fig. 7 extending between the vertical lines representing the intermediate and the clockwise positions of the rotor, it being noted that the declination of this line from left to right represents a selected position of adjustable inembers E0 relative to the axis of rotation of the rotor and that such declination may be increased or decreased respectively, according as the adjustable members 6l) are moved inwardly or outwardly from the selected location, such movement of the member 60 resulting in varying the effective spring length of fingers 21 cooperating with such adjustable members. The members 60 therefore provide an adjustable means for increasing or decreasing the forces exerted on the rotor by the flexible fingers 21 when the rotor is displaced toward its extreme clockwise position. It is to be noted that the fingers 21 and members 60 do not complete any electrical contact, but if such function is required it can easily be furnished by providing contact terminals 51 in place of the adjustable members 5D and by providing a iiexible connection between such lingers 'i1 and suitable terminal posts in the manner shown in Fig. l and previously described for the other pair of fingers 21.

The lingers 21, and cooperating terminals li? and adjustable members 80, therefore unctiton not only to establish electrical contacts of low Vresistance in one extreme position of the rotor (and can be arranged to establish similar contacts in the other extreme position as previously mentioned) but also function to bias the rotor to its intermediate position by developing torques which increase uniformly as the rotor is swung away from its intermediate position toward either extreme position.

The pole pieces 35 which support pivot plate 3&6 in a manner previously explained are assembled together in such a manner that when the roktor is in its intermediate position illustrated in Fig. 1, the opposite ends of magnetizable member 28 are disposed equi-distant from the confronting legs of the two pole pieces 35. The permanent magnet 43 supplying iux to pole pieces 35 establishes a field between such pole pieces With one of the pole pieces being the one pole and the other pole piece the other pole of such field, so that with armature member 28 equi-distant from the legs of such pole pieces -a net resultant force of zero magnitude Will be impressed upon the rotor due to the flux acting on magnetizable member 28. When, however, the rotor is swung to its extreme counterclockwise position, then member 28 has its opposite ends disposed adjacent to diagonally opposite legs of the two pole pieces 35 so that the member 28 forms a path of low reluctance for the flux circulating in pole pieces 35, while if the rotor is swung to its extreme clockwise position the opposite ends of member 28 are disposed adjacent to the other two diagonally opposite legs of pole pieces 35. The pole pieces 35 are spaced apart when assembled in the manner previously explained to establish this re lationship of member 28 and the legs of the pole pieces in the extreme positions of the rotor.

The fiux in the pole pieces 35 establishes on the rotor a torque which varies from a maximum when member 28 occupies a position adjacent to the two oppositely disposed legs of the pole pieces in one extreme position of the rotor, decreases non-uniformly to pass through the zero value when the rotor is positioned in its intermediate position, and then increases non-uniformly to another maximum value when the member 28 is disposed adjacent to the other two opposite legs of pole pieces 35. The torque exerted on the rotor by the eld due to permanent magnet 43 may be represented by the curve e of Fig. 1, it being understood that this curve reflects a certain level of magnetization of magnet 43. It is of course evident that the relative values of the torque due to the action of flux on member 28 may be altered by varying the level of magnetization of magnet 43, in which event the general shape of the curve will be maintained although the relative values of the torques will be increased or decreased according as the level of magnetization is increased or decreased, respectively. The magnetic fiux acting upon member 28 tends to bias the rotor to the nearest one of its two extreme positions and opposes movement of the rotor away from such extreme position toward its intermediate position. As indicated in Fig. 7, the torque exerted on the rotor due to flux acting on member 28 is opposite in sense to the torque due to the flexible ngers 21 and the relative values of these torques will be selected in such a manner that except in the intermediate position of the rotor, the torque due to magnet 43 always overcomes or exceeds the torque due to the lingers 27. The net resultant of the torque due to the ngers 21 (curves c and d) and to the magnet 43 (curve e) is represented by curve f of Fig. 7, which clearly indicates the degree by which the torque due to magnet 43 exceeds the torque due to the fingers 21. As can b e seen in Fig. 5, member 28 and fingers 21 lie in common' planes passing at right angles to the axis of rotation of the rotor so that the torques due to magnet 43 and fingers 21 are symmetrical with respect to the pivots 1 and 31 to minimize any unbalanced torque upon these pivots as fulcrums.

The spiral spring I6 carried on gear plate I2 provides a means for biasing the rotor to a. selected one of its two extreme positions defined by the armature stops 54. With the relay parts assembled in the manner previously described, when the rotor in its intermediate position illustrated in Fig. 1, and with the gear plate I2 freely movable in bore 3, the plate l2 will assume a position in which spring I5 is uniiexed so as not to impose any loading upon the rotor. Gear plate i2 may be moved relative to frame member I by means of a toothed key 10 insertable into opening I0 n the rear face of member I and having a projecting portion which extends through opening I I and beyond the rim of member I. The teeth of gear 1li will engage teeth I3 of plate I2 (see Fig. 6) and a handle 1I may be attached by a collar 12 to the extending portion of key 10 to provide a convenient means for rotating the key. Rotation of the key to cause plate I2 tov move in a direction opposite to that in which the rotor is caused to rotate in response to flux supplied from pole piece 2 to the magnetizable shoes I9, causes the rotor to swing in its counterclockwise direction to bring the magnetizable shoes I9 into engagement with core pins 65 of the counterclockwise armature stops 64, thereby preventing further rotation of the rotor. Continued rotation of key 10 in the same direction iiexes spring I5 and imposes a spring loading on the rotor which holds it constantly against its counterclockwise armature stops. As will be explained hereinafter, the plate I2 will be rotated suiciently by key 10 so as to cause the spring loading on the rotor to reach a certain value selected with respect to the energizing force available to supply flux to the pole pieces 2. When this position of plate I2 is determined, the plate will initially be locked into place by screws 13 carried in supporting member 4I effective when tightened down to force the plate I2 firmly against the base of bore 3 to prevent relative movement between the plate and member I. Solidiiiable material in its liquid state, such as molten lead, is then poured into the openings 9 on the rear face of member I so as to flow into the radial slots formed in the rear face of plate I2. The material when solidified rigidly keys together plate I2 and member I (see Fig. 6) to maintain the established relationship of these two members.

Spiral spring I5 is designed so that over the relatively small range of movement of the rotor between its two extreme positions the spring will impose upon the armature a torque which increases at a substantially uniform rate as the rotor moves away from its extreme counterclock- Wise position toward its extreme clockwise position. This torque may, for example, be represented by the curve g of Fig. 7, and it will be noted that this torque varies from a minimum value in the extreme counterclockwise position of the rotor to ar maximum value at the eXtreme clockwise position. The spiral spring torque g cooperates with the flexible finger torques c and d, and the torque e due to magnet 43, to establish on the rotor a resultant torque which may be represented by the curve h of Fig. 7. This resultant curve h representing the net torque broken away to show the position of mounting th ieehanism in bore C15. The bottom of here e holes e5 coizirnunicating neel portion ends CELL receive the ling 1- e nechanisin. @ther holes also D .1.. 1Q, ln Lne bot'. ni or boze e5 e neck .ie slot, ier in. housinf The ends of pole ly from frame member i project through openings Se to abut against magnetizable members 9B forming a part of a iux collecting means (see Figs. 9, 1l, and l2) mounted around reduced neck portion 36 of the housing. These ux collect-means include two strap assemblies each comprised (see Figs. 13 and 14) of two magnetizable members 3S and a cooperating magnetizable wedge member 9|. Non-magnetizable connecting strips riveted respectively to the two members Se of each strap assembly hold these members spaced apart from each other for per mitting insertion between them of the adjustable wedge member 9|. The inner edges of the members Se are shaped outer suriace of the red-.if r lr pne.. of the housing, and the strap assemblies are proportioned so that when assembled around the neck 86 as shown in Fig. 12 the outer end of one member SG abuts against one pole piece 2 of one of the two pairs of pole pieces mounted in frame member I, and the outer end of the other member 99 of that assembly abuts against one of the pole pieces 2 of the other pair. The right-hand pole pieces 2 of each pair (as viewed in Fig. l2) are thus connected together through the medium of the two magnetizable members 99 and the cooperating wedge member 9| comprising one of the two strap assemblies, while the other two (left-hand) pole pieces 2 are connected together by the other strap assembly. The strap assemblies when mounted on neck in the manner just described have their adjacent ends spaced apart from each other and are maintained in this spaced relation by non-magnetizable spacing members 93 provided with pins 94 which engage openings 95 provided in the ends of the members SQ. The spacing members 93 also are threaded to receive the ends of the bolts 88 which secure frame member in the bore 25 of the associated housing, the arrangement being effective when bolts 88 are tightened down to hold the operating mechanism in its housing and the magneticable members, 90 of the strap assemblies tightly into abutting relation with the ends of the associated pole pieces 2.

Each spacing member 93 is provided with a spring IG secured to the member by a bolt 'i1 for assisting in maintaining the strap assemblies properly positioned in the neck of housing 83, the spring being disposed between the associated spacing member 93 and the sidewall of the slot nearest bore S5 of the housing. An insulating strip 'i8 is provided between the strap assemblies and the other sidewall of the slot for insulating the assemblies from the current carrying housing so as to prevent passage of load current through the strap assemblies.

Each adjustable wedge member 9| and its twoY associatedmagnetizable members. 90 have their adjacent ends formed with matching tapers, and the two wedge members are connected together by a rod 95 extending through an opening Si drilled in neet; and con vc. ier end to threaded drive rods Sii mounted in inner and outer guide blocks 9B and |08, respec "vely. The guide blocks are riveted respectively to the con necting strips 92 of the associated strap assembly, while the wedges 9| are threaded to engage the drive rods 98 and are mounted between the connecting strips 92 for movement toward or away from the neck 86, the strips 92 confining the sides of wedges 9| to prevent them from turning. One of the outer guide blocks |08 has an extension on which are formed teeth lill which mate with teeth formed on an operating nut li carried on an extension of one of the drive rods S8 which is also provided with a locking nut |53, eiiectivc when tightened down to lock the tee-th nut |92 into engagement with'the teeth formed on guide block iElD. The nuts |2 and |33 are drilled with holes some of which match or align in the various different positions of the nuts, to provide a means for inserting a locking wire |34 which when its ends are sealed provides a teil-tale insuring against unauthorized operation of the operating nut |02.

Before attaching and sealing locking wire 04, the nut l0?. will be backed off nut |62 which is freely movable along its drive rod 93 and is operatively connected thereto in any suitable manner, as by providing rod 98 with projections |05 mat-- ing with slots formed in the hub of nutl |D2 so `that when nut |32 is withdrawn from the te th of guide block |63, the nut may be turned to rotate its drive rod 98, the connecting rod 8E, and the other drive rod 98. The two drive rods 952 are oppositely threaded, that is, one is formed with right-hand and the other with left-hand threads which engage corresponding threads of the associated adjustable members 9| so that rotation of nut |02 will cause both adjustable wedge members 9| to move simultaneously in opposite directions relative to neck 85, both members 9| moving in unison either toward or away from the de'^eno` ing upon the direction oi' rotation of nut |52. This movement will decrease 0r increase respectively the air gap between wedges 9| and their associated magnetizable members S to decrease or increase the reluctance of the magnetic path comprised of the two mag netizable members 9i! and the intervening adjustable member 9|.

The iiux collecting means may besnitably enclosed as by a cellar i preierabhv formed ci insulating mater as may be made icm the outs? 83 to the terminals di of the mechanis i therein, by wires iis corniectee to and brought out through openii The wires y diiernal cir .introiled by the re aff t in 8 be connected to such external circuits lug coupler me is illustrated in 9 and The plug coupior com mating sets or" male and female terminals, one set of such terninals lil mounted in an insulating bloei; H2 fastened to the sides of housings 83 by boits ||3 and connected to wires ii'il which pass through openings |35 (see Fig. 1G) provided in the sidewalls oi the housing, and the other set of connectors I6 being carried in a detachable plug coupler H1 provided with terminals H8 for at- 2 taehingexternal circuit wires ||9 (see Fig.. S).

17. A dust cover |20 (see Fig. 9) inserted between insulating block H2 and plug ||1 ts tightly around the block and plug to provide a dustproof seal for the mating plug coupler terminals. The various units are assembled together by tightening down a nut |2| threaded onto a bolt |22 carried in block I i2 and projecting outwardly from plug I I1 through an opening provided therein.

The terminals I I8 carried in plug I1 are grouped in two spaced pairs so arranged that plug H1 may be attached to terminals IH carried vby block H2, in either of two positions spaced 180 apart. As indicated conventionally in Fig. 8, the two terminal posts 41 of a relay are connected to diagonally opposite terminals of the plug coupler assembly so that regardless of the position in which plug ||1 is attached to the coupler assembly, the same two diagonally opposite terminals I8 of the plug wl mate with-the two terminals I I I connected to a particular relay, thereby assuring that the external connections to the relays RI and R2 will always be made with the proper relay terminals 41 in any position in which plug I I1 is attached to the mating block member Each one of the extended portions ofthe pole pieces 2 projecting through openings 81 in the .bottom of hollow housing 83 to abut against the outer end of the associated member 90, effects a continuance of the magnetic path comprised of such abutting member. The mechanisms mounted in housings 83 connected in series in the load circuit will be supplied through the magnetizable pole pieces 2 with flux from the eld established around reduced neck portion 86 of the associated housing. The magnitude of this eld will be directly proportional to the current supplied to the load through the housings 83. The pole pieces 2 and the associated magnetizable shoes I9 provide a path of relatively low reluctance across the adjacent ends of the two strap assemblies vspaced apart by spacing members 93, and a portion of the flux of the external magnetic field surrounding neck 86 willv be diverted or shunted through the pole pieces 2 into the hollow bore 85 to pass through the magnetizable shoes I9, therebyexerting on the shoes a force tending to bring the shoe faces into alignment with the exposed -faces of the pole pieces 2. At a certain level of l"current in the relay housing 83, this forcev on the magnetizable shoes I9 will cause the rotor to operate from its biased counterclockwise position to its clockwise position, thereby opening the con- `-tacts21-51 of the relay. After the relay has picked up to open its contacts 21-51, a decrease Kin the current value carried by housing 83 below the level determined by the per cent release to :pick-up ratio of the relay, will cause the rotor to .swing back' to its counterclockwise position, as

.previously explained in detail hereinbefore.

. rThe particular level of current in the housing ..183 at which the rotor mounted therein will be ,picked up, will be determined (within limits, of bourse) by the adjustment of wedges 9| relative .to their associated members 99. If the wedges 9| .are positioned near neck 86, the spacing between j members 90 and the wedge will be smaller than is the case with the wedges moved away from the lneck, consequently the reluctance of the strap assembly varies from a lower to a higher value according to the position of wedge 9| relative to its associated members 90 abutting against the pole pieces 2. The proportion of the flux threadingthestrap assemblies at any glvenlevelof current in housing 83 accordingly may be varied by adjusting the position of vwedges 9|, so that the magnitude of ilux supplied from the strap assemblies to the pole pieces 2 may likewise be varied. The relative dimensions of the members 90 and 9| will be selected with respect to the particular range of operation of the relays so that by slight adjustments of the position of wedges 9|, operation of the relay can be obtained at any particular current value over a relatively wide range. The adjustment of the wedges 9| to select the particular current value of operation of the relay will be eiected by operating nut |02 in the manner previously mentioned.

It is to be noted that the relay armatures in housings 83 respond directly to the ilux established around neck 86 of the housing, and since the strength of Athis eld is'directly proportional to the current in the housing, the operation of the relays will not be aiectsd in way by variations in ambient temperature or, in other words, the relays will always respond directly to the value of current in the housings. It should also be noted that the armatures, mounted within the hollow space entirely enclosed by the current-carrying sidewalls of the housing members 83, will respond to the iiux diverted or shunted into the hollow space by the pole pieces 2, but will not be affected by current flowing in the housing sidewalls. due to the neutral magnetic space inside of the hollow housings 83. The relay armatures therefore will be operated upon only by flux led into the hollow space of the housings from the external field established around the housing, but will not be affected by current flowing in the conductive sidewall of the housing.

The use of two pairs of pole pieces 2 in a relay embodying my invention not only affords a balanced system of forces on the armature assembly. as previously mentioned, but also minimizes the effect of stray magnetic fields on the relay armature. That is to say, if a stray magnetic eld should exist at the point where a relay embodying my invention is mounted, any force exerted on the rotor by Such iield passing through one of the magnetizable shoes I9 will be substantially balanced out by the force due to such eld on the `other magnetizable shoe I9, it being assumed that the direction of the stray eld through the two shoes will be in the same direction. Additional ,be employed alone, in which event only one housing 83 will be required and will be bolted to a cover element shaped to enclose the open end of bore 85 and provided with a tang on the opposite end, the cover element replacing the other housing 83. Also, it should be understood that the principle of operation of the relays shown in Figs.

v8-12 inclusive, permit the relays to be supplied with flux from fields other than those established around power bus bars. In other words, the magnetizable strap assemblies which connect together .one of the pole pieces of each pair, and which are disposed in the magnetic eld established around 4vthe neck of housing 83, may if desired be disposed in the magnetic field of an electrical coil disposed on such a strap assembly, or in other words the pole pieces 2 may be connected together by magnetizable core members on which are mounted magnetizing coils. In such an event the coil or coils will be energized in such a manner that nur: is caused to flow in opposite directions in the two core members so as to pass in series through such cores, the two pole pieces o each pair, and the magnetizable shoes i9. In this construction the operating unit and energizing means may be mounted in a suitable relay housing of common construction.

From the foregoing description it is readily apparent that I have provided a novel and improved form of electrical relay comprised of sturdy, rugged parts with certain of the relay elements maintained against relative displacement by solidiied material (such as lead), the moving parts of the device balanced both statically and dynamically so as to avoid undue wear on the pivots and assure proper operation in service, and the forces applied to the rotor arranged symmetrically in order to minimize unbalanced forces. All of these factors contribute toward making a relay embodying my invention stable in operation when subjected to severe vibrations, shocks and jars. The relay design also affords protection against operation due to stray magnetic elds by use of the two pairs of pole pieces cooperating with two magnetizable armatures.

An important advantage of my invention is the method or developing and combining the torques exerted on the relay rotor to obtain the desired resulting operation. rhe rotary torque developed due to the energizing iiux in the relay is balanced n against the spiral spring torque, while the spring torques of the flexible fingers work against the torque due to the permanent magnet. The combined resultant torque developed by the relay provides for a snap action between armature positionsv while affording a high ratio of release to pick-up. The relay is extremely accurate in operation, and is readily adjustable to vary the per cent release ratio by simple adjustments in the magnetization of the permanent magnet.

A further advantage of my invetnion resides in its ease of application as a bus bar relay. The relay design permits of operation in response to flux from an external eld surrounding a conductor, and enables the armature to be mounted within the neutral magnetic space of a hollow conductor which carries the energizing current for the relay. The supply of ilux to the armature is furnished from means positioned in the external eld and adjustable for varying the level of the energizing current to which the relay will respond. This adjustment is independent vof the adjustment of the per cent release of the relay. The relay operation is directly responsive to the strength of the external magnetic field, and since this strength is directly proportional to the current, the operation of the relay is entirely independent of variations in ambient temgperature,A any change in temperature merely varying the amount of heat required to be dissipated by the relay housing.

Although I have herein shown and described only one form of an electrical relay embodying my invention, it is understood that various changes and modications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a hollow current carrying element adapted to carry electric current in a direction such that the magnetic iield produced by the current now is external to the element, a plurality of magnetizable strap assemblies disposed around said element so as to be threaded in series by iiux of said external cld with the said magnetizable strap assemblies having their adjacent ends separated from each other, each said strap assembly comprising: a pair of magnetizable members maintained spaced apart, a third magnetizable member disposed between the pair of magnetizable members, the adjacent ends of said third and of said pair of magnetizable members of an assembly being formed with matching tapers so as to provide varying air gaps between such adjacent ends depending upon the relative positions of said members, means for simultaneously moving the third magnetizable member of each of the plurality of magnetizable strap assemblies relative to its pair of magnetizable members so as to eiect a uniform change in air gaps for each strap assembly, and pole pieces extending through the walls of said conductor into cooperating relation with the adjacent ends of said strap assemblies for conducting flux from said external field into the hollow space inside said conductor.

2. In combination, a conductive element having a longitudinally extending bore, magnetizable members disposed about said element to form two magnetic paths threaded in series by flux when a eld is established by current in said element, the adjacent ends of said two magnetic paths being spaced apart, two pairs of magnetizable pole pieces extending from the inside of said bore to the outside of said element each abutting respectively with an end of said magnetic paths, a movable member mounted in said bore, two armatures carried by said movable member. for cooperating respectively with the two pairs of pole pieces, said movable member operable between two extreme positions in one of which the armatures provide a path of lower reluctance across the pole` pieces than in the other, means for biasing said movable member to its said other extreme position, contact means carried by said movable member for closing contacts in at least one of its two extreme positions and eiective to bias said movable member to a position intermediate its two extreme positions, and means coacting with said movable member to bias it to its nearest extreme position by a force exceeding the force exerted on said movable member by said Contact means.

3. In an electrical control system for establishing a control in response to electric current supplied to a load from a source of current, a hollow conductor connecting said load with said source for supplying electric current to said load with the current flowing in said conductor in a direction such that the magnetic field produced by the current iiow is external to the conductor. relay means housed within the hollow portion of said conductor and including an armature supplied with flux from said external field for operating said relay means, and means operated by said relay means.

4. In a diesel-electric locomotive having a prime mover driving an electrical generator, said locomotive provided with wheel-driving electric motors, a control system for establishing a control in response to current supplied from said generator to said motors, comprising a. hollow conductor, means connecting said motors and generator for supplying electric current to the motors and including said hollow conductor arranged so that the current supplied to the motor flows in said conductor in such a direction that the magnetic eld produced thereby is external to said conductor, relay means mounted inside said conductor and having an armature included in a magnetic circuit supplied with flux from said external eld and responsive to such flux, and means controlled by said relay means.

5. In an electrical relay, in combination, a frame member, an armature member, means carried by said frame member mounting said armature member for movement between two extreme positions, means carried by said frame and armature members biasing said armature member to an intermediate position, a iirst armature means carried by said armature member, means carried by said frame member cooperating with said rst armature means to provide a iirst magnetic circuit including said first armature means and adapted to be supplied with magnetic iiux to bias said armature member to the nearest one of its said two extreme positions, means operatively 'connected with said frame and armature members biasing said armature member to a selected one of its said two extreme positions, a second armature means carried by said armature member, and other means carried by said frame member cooperating with said second armature means to provide a second magnetic circuit independent of said rst magnetic circuit and adapted to be supplied with magnetic flux to operate said armature member to the other of its said two positions.

6. In an electrical relay, in combination, a frame member, an armature member mounted in said frame member for movement between two extreme positions and biased to a selected one of its said two extreme positions, a first armature means carried by said armature member, means carried by said frame member cooperating with said rst armature means to provide a first magnetic circuit including said first armature means and adapted to be supplied with magnetic flux to bias said armature member to the nearest one of its said two extreme positions, a second armature means carried by said armature member, and other means carried by said frame member cooperating with said second armature means to provide a second magnetic circuit independent of said iirst magnetic circuit and adapted to be supplied with magnetic iiux to operate said armature member to the other of its said two positions.

7. In an electrical relay, in combination, a `frame member, a rotor supported by said frame member for rotation between two extreme positions, pole pieces supported by said frame member, armature means carried by said rotor cooperating with said p'ole pieces for operating said rotor to one of its said two extreme positions when :magnetic iiux is supplied to said pole pieces, and means biasing said rotor to the other of its said ltwo extreme positions, said means comprising an adjustable member supported by said frame member so as to permit relative movement be- 'tween said frame and adjustable members, a

spiral spring connected at one end to said rotor force which can be varied by varying the relative positions of said frame and adjusting members,

and means carried by said frame member for locking said frame and adjusting members against relative movement.

8. In an electrical relay, in combination, a frame member, a rotor supported by said frame member for rotation between two extreme positions, pole piecessupported by said frame member. armature means carried by said rotor cooperating with said pole pieces for operating said rotor to one of its said two extreme positions when magnetic flux is supplied to said pole pieces, and means biasing said rotor to the other of its said two extreme positions, said means comprising an adjustable member supported by said frame member so as to permit relative movement between said frame and adjustable members, a spiral spring connected at one end to said rotor and at its other end to said adjustable member, said spring formed and connected so as to urge said rotor to said other extreme position by a force which can be varied by varying the relative positions of said frame and adjusting members, and said frame and adjusting members being formed to receive a solidiflable material in its iluid state, whereby said frame and adjusting members can be locked into engagement by the introduction of said material and its subsequent solidication. y

9. In combination, a frame member, a rotor pivotally supported by said frame member for rotation between two extreme positions, pole pieces supported by said frame member, armature means carried by said rotor cooperating with said pole pieces for operating said rotor to one of its said two positions when magnetic iiux is supplied to said pole pieces, an adjustable member carried by said frame member and disposed between said armature means and said frame member' movable relative to said rotor, a spiral spring connected at one end to said rotor and at the other end to said adjustable member, said adjustable member being provided with serrations, a manually operable adjusting member provided with serrations and adapted to be mounted in said lframe member with the serrations of b oth said members in mating engagement, whereby to adjust the position of said adjustable member relative to said rotor when the parts are in assem- -bled relationship.

10. The combination with a hollow housing, of a frame member mounted in said housing, a rotor` pivotally supported by said frame member for rotation between two extreme positions, pole pieces supported by said frame member, armature means carried by said rotor cooperating Vwith said pole pieces for operating said rotor to one of its said two positions when magnetic ux -is supplied to said pole pieces, an adjustable member carried by said frame member and disposed-between said armature means and said -frame member movable relative to said rotor, a spiral spring connected at one end to said rotor and at the other end to said adjustable member, and means manually operable from outside said housing for adjusting said adjustable member relative to said rotor when said rotor and adjustable member and frame member are in assembled relationship in said housing.

11. In combination, a frame member, a rotor pivotally supported by said frame member for rotation between two extreme positions, pole pieces supported by said frame member, armature means carried by said rotor cooperating with said pole pieces for operating said rotor to one of its said two positions when magnetic ux issupplied to said pole pieces, an adjustable membercarried said frame member and disposed between said armature means and said frame member movable relative to said. rotor, a spiral spring connected at one end to said rotor and at the other end to said adjustable member, saidv adjustable member being provided with serrations, a removable key provided mating, serrations, said frame i leniber being formed 'to receive and guide said sc-y with its serrations in engagement with the serrations of said adjustable member, said key being operable. when inserted in said frame member to adjust the position of said adju-stable member relative to said rotor when said rotor: and adjustabie and frame members are assembled in operativ-e relationship.

i2. In nation, a frame member, a rotor pivotally supported by said frame member for rotation between two estreme positions, pole pieces ecu-red to said frame member providing two pairs oi' pole in spaced confronting relation, an armature carried by said rotor and having its ends disposed between the confronting faces oi' said pole pieces for connecting diagonally opposite pairs of faces in each of the two extreme positions ci said rotor, a magnet connected with said pole pieces, said pole pieces and armature forming magnetic circuit for flux supplied by said magnet whereby said armature magnetically biases said rotor to its nearest extreme position, means carried said frame membe biasing said rotor to a selected one oi' its said two extreme positions, another armature carried by said rotor, cooperating pole pieces carried by said raine member, said other armature and cooperatingpole pieces providing another magnetic circuit separate and apart from the first mentioned magnetic circuit, and means supplying iux to said other magnetic circuit whereby said rotor is operated to the other of its said two positions.

i3. In combination, a frame member, a rotor pivotally supported by said frame member for rotation between two extreme positions, magnetizable pole pieces secured to said frame member providing Itwo pairs of pole faces in spaced confronting relation, an armature carried by said rotor and having its ends disposed between the confronting faces of said pole pieces for connecting diagonally opposite pairs of faces in each of the two extreme positions of said rotor, a magnet connected with said pole pieces, said pole pieces and armature forming a magnetic circuit for flux supplied by said magnet whereby said armature magnetically biases said rotor to its nearest extreme position, contact means comprising spring members and xed members carried by said frame member and rotor establishing electrical contact in the extreme positions of said rotor and effective to urge said rotor to a position midway between its said two extreme positions, means operatively connected with said rotor and said frame member biasing said rotor to a selected one of its said two extreme positions, another armature carried by said rotor, cooperating pole pieces carried by said frame member, said other armature and cooperating pole pieces providing, another magnetic circuit separate and apart from the rst mentioned magnetic circuit, and means supplying flux to said other magnetic circuit whereby said rotor is operated to the other of its said two positions.

14. In an electrical relay, in combination, a frame member, a rotor pivotally supported by said frame member for rotation between two extreme positions, biasing means comprising a.

iirst armature means carried by said rotor and cooperating pole pieces carried by said frame member providing two pairs of pole pieces in spaced confronting relation with said armature having its ends disposed between the confronting faces of said pole pieces to form a rst mag'- netic circuit adapted: to be supplied with ux whereby said rotor is biased to the nearest one of its said two extreme positions, Contact means comprising cooperating iingers and xed members carried by said frame member and rotor establishing electrical contact in at. least one of said two extreme positions of said rotor,A said contact means biasing said rotor to a position midway between its said two extreme positions, said biasing means and contact means being. so located relative to each other and to the axis of rotation of said rotor that the forces exerted thereby on said rotor have substantially equal moments about the points of support of said rotor, whereby to minimize the resultant torque developed by such forces about the points of support, spring means operatively connected with said frame member and said rotor biasing said rotor to a selected one of its said two extreme positions, and electromagnetic means comprising other pole pieces carried by said frame member and a second armature means carried by said rotor cooperating with said other pole pieces to provide a second magnetic circuit independent of said first magnetic circuit and adapted tobe supplied with ux to operate said rotor to the other of its said two extreme positions, said electromagnetic ine-ans and said spring means with its connections to said frame member and rotor being solocated relative to each other and to the axis of rotation of said rotor that the forces exerted thereby on said rotor havey substantially equal moments about the points of support of said rotor, whereby to minimize the resultant torque developed by such forces about such points of support.

15. In a relay, a. rotor pivotally mounted for movement between two extreme positions, means including a permanent magnet provided with a magnetic circuit carried in part on. said rotor magnetically biasing said rotor to the nearest of its said two extreme positions, contact means carried in part by said rotor establishing an electrical contact in the extreme positions of said rotor eiective to bias said rotor to an intermediate position, other means biasing said rotor to a selected one of its said two extreme positions, and electromagnetic means provided with a magnetic circuit carried in part on said rotor separate and apart from the magnetic circuit of said permanent magnet, for operating said rotor to the. other of itsr said extreme positions.`

16. In a relay, a rotor pivotally mountedfor movement between two extreme positions, two magnetizable armature means carried by said rotor and included respectively in two separate and distinct magnetic circuits, a rst source of magnetic flux for one of said magneticl circuits biasing said rotor to the nearest one of its said two extreme positions, a second source of magnetic ux for the second of said magnetic circuits for operating said rotor to a selected one f its said two` positions, means biasing said rotor to the other one of its said two extreme positions. and contact means operated by said rotor establishing an electrical contact in at least one of the two extreme positions of said rotor and urging said rotor to an intermediate pazisittorx.k

17. In a relay, a hollow conductive housing adapted to carry the exciting current of the relay, a rotor pivotally mounted in said housing for movement between two extreme positions, two magnetizable members carried by said rotor included respectively in two separate and distinct magnetic circuits, a rst source of magnetic energy mounted in said housing supplying flux to one of said magnetic circuits, the iiux in said rst magnetic circuit biasing said rotor to the nearest one of its said two extreme positions, means supplying the second of said magnetic circuits with ilux when a iield is set up by current in said housing, the flux in said second magnetic circuit tending to operate said rotor to a selected one of its said two extreme positions, means biasing said rotor to the other of its said two extreme positions, and contact means operated by. said rotor establishing an electrical contact in said extreme positions and urging said rotor to a position intermediate its said two extreme positions.

18. In a relay armature assembly, a shaft, an insulating body molded on one end of said shaft, the free ends of said shaft and body being adapted to be pivotally supported in axial alignment, iiexible fingers molded in said body and extending outwardly therefrom, an armature molded in said body and extending through said body to project on opposite sides thereof, a nonmagnetizable spider provided with a plurality of radial arms, a plurality of magnetizable members one for each radial arm carried at the outer ends thereof, said spider formed with a central opening for receiving said shaft, and means for securing together said shaft and spider when assembled with said shaft projecting through said spider opening.

19. As a new article of manufacture, a relay housing adapted for interposition as a current carrying element in a circuit supplying electrical current from a source to a load, saidhousing formed of conductive material and provided with a longitudinally extending opening adapted to receive the relay operating mechanism.

20. As a new article of manufacture, a relay housing adapted to be connected as a current carrying element in a circuit supplying electri- .calcurrent from a source to a load, said housing formed of conductive material with a longitudinally extending opening formed at one end to receive the relay operating mechanism, said housing being formed intermediate its other end and said opening with a reduced neck portion.

21. In an electrical relay, a housing of conductive material adapted to be connected as a -current carrying element in a circuit supplying -electrical current from a source to a load, and

tor, an armature mounted in said conductor for movement between two extreme positions and biased to one of said positions, and means linking said armature with the iield set up when current flows in said conductor, for operating said armature to the other of its said two positions.

24. In an electrical circuit supplying electric current to a load, two relay housings each formed of electrically conductive material and having an opening extending from one end of the housing toward the other, said relay housings secured together with the ends provided with openings in abutting relation and with their opposite ends connected respectively in said load circuit, whereby said two housings are included in series in said load circuit and carry the load current in such a direction that the magnetic iieldproduced by the current iiow is external' to the housings, two relay means mounted respectively inside said two housings and each including an armature, and means associated with each of said housings for diverting iiux from the field external to the housing into said opening and through the associated armature lier operating that armature.

25. A relay comprising, in combination, a housing of conductive material adapted to be connected at its opposiLe ends in a circuit supplying electrical current from a source to a load, said housing functioning as a current carrying element when current is supplied from the source to the load, said housing being provided with an opening extending from one end of the housing toward the other, an armature mounted in said opening, and means linking said armature with the field set up when current ows connected at its opposite ends in a circuit supplying electrical current from a source to a load, said housing functioning as a current carrying element when current is supplied from the source to the load, said housing provided with an opening extending from one end of the housing toward the other, an armature mounted in said opening, a magnetizable member disposed about said housing between the inner end of said opening and said other end of said housing, rsaid magnetizable member arranged to provide a magnetic circuit including an air gap for the iiux set up when current flows in said housing, and means magnetically connecting said armature across said air gap.

27. A relay comprising, in combination, a lhousing of conductive material adapted to be connected at itsopposite ends in a circuit supplying electrical current from a source to a load,

said housing functioning as a current carrying element when current is supplied from the source to the load, said housing provided with an opening extending from one end of the housing toward the other, an armature mounted in said opening, a'plurality of magnetizable members disposed about Lsaid `housing between its said other end and the inner end of said opening, said magnetizable members disposed to be threaded in series by ux set up when current flows insaid housing, and arranged to provide a magnetic circuit including an air gap for such plying electrical current from a source to a load,

said housing functioning as a current carrying element when current is supplied from the source to the load, said housing provided with an opening extendingfrom one end of the housing toward the other, an armature mounted in said opening, a plurality -of magnetizable members disposed about said housing between its said other end and the inner end of said opening, said magnetizable members disposed to be threaded in series by flux set up when current flows in said housing, and arranged to provide a magnetic circuit including an air gap for such flux, means for adjusting said magnetizable members relative to each other for varying the reluctance of said magnetic path, and pole pieces extending from within said opening to said magnetizable members connecting said armature across said air gap.

29. A relay comprising, housing of electrical adapted to be connected at its opposite ends in a circuit supplying electrical current from a source to a load, said housing being provided with an opening extending from one end of said housing toward the other, a movable .member mounted in said opening for movement between two extreme positions .and biased to one such position, a plurality of armatures carried by said movable member within said opening, a plurality of magnetizable -members disposed about said housing between its said two ends, said magnetizable members disposed to be threaded in series by ux set up when current flows in said housing, and arranged to provide a magnetic circuit for said ux including a plurality of air gaps one for each of said armatures, means for adjusting said magnetizable members simultaneously for varying the reluctances of the magnetizable members, and a plurality of pairs in combination, a

of pole pieces one for each armature extending from within said opening to .said magnetizable members, each pair of pole pieces magnetically connecting its associated armature across the associated air gap, whereby said movable membei' is operated to the other of its two positions by flux supplied to said armatures when Va field is established by current in said housing.

30. In a relay, in combination, a hollow conductor adapted to carry the exciting current for the relay in a direction such that the magnetic eld produced by the current flow is external to the conductor, a magnetic circuit for the flux of said external field comprising magnetizable members disposed around said conductor so as to be threaded in series by said .flux with said magnetizable members having their adjacent ends separated from each other by air gaps, a rotor mounted inside said hollow conductor for rotation between two extreme positions, van armature mounted on said rotor, pole pieces extending through the walls of said conductor and forming with said armature a magnetic circuit connected across said air gaps through which flux from said external field is diverted through said armature for operating said rotor to one of its two positions, means biasing said rotor to the other one of its said two extreme positions, Contact means operated by said rotor establishing electrical contact in the extreme positions of said rotor and tending to urge said rotor to a position midway between its extreme positions, and means biasing said rotor to the nearest of its said two extreme positions.

31. In a relay, a housing of conductive material adapted to be connected at its opposite ends in a circuit supplied with electrical current, magnetizable members disposed about said housing and arranged to provide a magnetic circuit including an air gap for 'the iiux set up when current is supplied to said housing, said housconducting material ing being formed with an vopening extending from one of its ends toward vthe other, two pole pieces engaging the opposite ends of said air gap, said pole pieces extending from said magnetizable members through said .housing into said opening, and a relay means mounted entirely within said opening, said relay means including a rotor supported for movement between two extreme positions and biased to one such position, an armature carried by said rotor cooperating with said two pole pieces for operating said rotor against rits bias to the other of said two positions in response to current supplied Ato said housing, contact means operated by said Vrotor establishing electrical contact in the extreme positions of said rotor and biasing said rotor to a position midway between its said extreme positions, and means biasing said rotor to 'the nearest of its said two extreme positions.

32. relay comprising a housing of kelectrical conducting material adapted to be connected at its opposite ends in a circuit supplying electrical current from a source to a load, said housing 'being provided with an opening extending from one end of said housing toward the other, a rotor mounted in said housing for operation between two extreme positions, an armature carried by said rotor, magnetizable elements disposed about said housing between its two ends and arranged to provide a magnetic circuit including an air gap for the ilux set up when current is supplied to said housing, pole pieces extending through 'said housing connecting said armature across said air gap, whereby said rotor is operated to one of its said two positions when current is supplied to said housing, means biasing said rotor to the other of its said two positions, contact means operated by said rotor establishing electrical contacts in the extreme positions of said rotor and biasing said rotor to a position midway between its extreme positions, and means biasing said rotor to the nearest of its said two positions.

33. In a relay comprising a housing of electrical conducting material adapted to be connected at its opposite ends in a circuit supply- -ing `electrical current from a source to a load, said housing being provided with an opening extending from one end of the housing toward the other, a rotor mounted in said opening for operation between two extreme positions, a plurality of armatures carried by said rotor, magnetizable members disposed about said housing to provide a magnetic circuit for the flux se't up when current is supplied to said housing, said members arranged to provide a plurality of air gaps in said magnetic circuit one for each armature, a pair of pole pieces provided `ior each c said armatures, connecting its associated larmature across the respective air gap, whereby said rotor is operated to one of its said two positions in response to current supplied to said housing, means for adjusting each of said magnetizable members simultaneously for varying the reluctance of said magnetic circuit, means biasing said rotor to lthe other of its said two positions, contact means operated by said rotor establishing electrical contacts in the extreme positions of said rotor and biasing said rotor to a position midway between its said extreme positions. and means biasing said rotor to the nearest one of its said two extreme positions.

34.111 combination, a hollow conductor 

